This is... sort of a feature I forgot to mention; as the name implies, it's meant to be an index of your language sorted by words in the language used for definitions, so you can have a two-way bilingual dictionary. It will be auto-populated if your definition starts with single words separated by commas, semicolons, or periods.
Here's Lilitika's, for comparison:
http://memory.rhetori.ca/?id=310&mode=reverse
The key and unique benefit is that you can enter multiple words here on different lines, and the word will show up under multiple headwords in the reverse view. Handy if your native language is full of common synonyms, or if you want to clarify that a concept maps unevenly onto near-synonyms in your native language. The definition is shown in the reverse view to (hopefully) make it easier to see at a glance when word relationships might be asymmetric.
If you click the link to view entries without reverse keywords (e.g.
for pre-Perà), you'll be shown a UI that will help you in identifying the words that have definitions that are unparseable. This feature is not compatible with
the importer's mass-overwrite feature (as that
currently deletes entries entirely) but the importer can include reverse keywords with new entries.